class_inheritable_accessor should let subclasses inherit from the superclass's attribute

This is expected behavior. I found following test.

  def test_inheritance
    @klass.class_inheritable_accessor :a
    @klass.a = 'a'

    @sub = eval("class FlogMe < @klass; end; FlogMe")

    @klass.class_inheritable_accessor :b

    assert_respond_to @sub, :a
    assert_respond_to @sub, :b
    assert_equal @klass.a, @sub.a
    assert_equal @klass.b, @sub.b
    assert_equal 'a', @sub.a
    assert_nil @sub.b

    @klass.b = 'b'
    assert_not_equal @klass.b, @sub.b
    assert_equal 'b', @klass.b
    assert_nil @sub.b

    @sub.a = 'A'
    assert_not_equal @klass.a, @sub.a
    assert_equal 'a', @klass.a
    assert_equal 'A', @sub.a

    @sub.b = 'B'
    assert_not_equal @klass.b, @sub.b
    assert_equal 'b', @klass.b
    assert_equal 'B', @sub.b
  end

As you can see

@klass.b = 'b'
assert_not_equal @klass.b, @sub.b

I am adding two lines to the doc to make it clear that child copies attributes from parents when subclass is created.

Thanks for your documentation update. It states very clearly the implementation rationale.

However, I believe that implementation violates the Principle of Least Surprise, and that the behavior, despite being documented and tested, is not expected.

What do you think?